Coryphophthalmus troglophilus Kaplin, 2020

Kaplin, Vladimir & Vargovitsh, Robert S., 2020, New species of bristletails of the family Machilidae (Microcoryphia) from caves in Abkhazia and Ukraine, Zootaxa 4885 (4), pp. 530-540 : 532-536

Coryphophthalmus troglophilus Kaplin , sp. nov.

Figs. 2–14

Diagnosis. Coryphophthalmus troglophilus sp. nov., with 2 + 2 eversible vesicles on urocoxites II–IV, belongs to the subgenus Coryphophthalmus s. str., a group of species with long thin chaetae on the legs, clypeus and maxillary palpomeres 2‒4, but lacking on male labial palp; without needle-like macrochaetae on legs. Only one species, C. abchasicus ( Kaplin, 2017) is affiliated to this group other than the new species ( Kaplin, 2017).

Description. Body length of males 7.0– 7.3 mm, females 7.2–8.2 mm; width of males and females 1.8–2.1 mm; antennae length of males 8.5–8.7 mm, female 6.8 mm (slightly broken); cercus length of males 3.8 mm, females 3.6–4.2 mm; total eyes width of males 0.86–0.88 mm, females 0.86–1.00 mm; eye length of males and females 0.43–0.46 and 0.44–0.48 mm, respectively; paired ocelli width of males 0.26–0.27 mm, females 0.23–0.26 mm; paired ocellus length of males and females 0.15–0.16 and 0.13–0.14 mm, respectively; coxal styli length of males 0.65–0.70, females 0.60–0.65 mm; ovipositor length 2.3–2.6 mm.

General body color (in ethanol) whitish or light yellow, almost without hypodermal pigment. Antennal base, frons, gena, lateral sides of clypeus, basal parts of mandibles, thoracic sterna with brown-violet hypodermal pigment of light to medium intensity. Scale color on surface of body grey, dark grey, almost white and black, light brown or brown, spotted on the upper side of body ( Fig. 2 ). Antennae of males and females slightly longer than body. Distal chains of male and female flagella divided into 8–12 annuli. Аpical, 3rd, 5th and 7th annuli of distal chains with one or two basiconic sensilla of D form; each annulus of chains also with one “rosette-shaped” sensillum. Clypeus and labrum of male with long thin chaetae. Cerci of males and females about 0.50–0.55 times body length, divided into 22–23 annuli, with apically bifurcated spikes. Two distal annuli of cerci without lateral hyaline spines. Remaining cercal annuli with 1–5 inner lateral spines in both sexes.

Compound eyes round, green or dark green (in ethanol). Length to width ratio of compound eye 1.00– 1.03 in both sexes; ratio of line of contact to length of male and female eyes 0.50–0.53 and 0.42–0.46, respectively. Paired ocelli submedian, pyriform, dark brown with narrow white borders. Ratios of width to length of male and female ocelli 1.7 and 1.8, respectively. Ratio of distance between inner and outer margins of ocelli to total width of compound eyes 0.16–0.18 and 0.64–0.66 eye in both sexes, respectively ( Fig. 3 ).

Apical maxillary palpomere 0.55–0.65 times (male) and 0.72–0.75 times (female) that of the preceding one, ratio of length of 5th and 4th palpomeres 1.3 in male and 1.4 in female. Dorsal surface of 7th, 6th and 5th palpomeres of maxillary palp with 10–11, 13–14 and 3–4 hyaline spines in male, and 12–14, 14–16, and 4–7 spines in female, respectively. Underside of palpomeres 2–4 of male maxillary palp with relatively numerous and long thin chaetae, missing on the dorsal surface of male labial palpomeres ( Fig. 4 ). Apical labial palpomere triangularly oval, 2.3–2.5 times (male) and 2.6–2.7 times (female) longer than wide, with 30–35 sensorial cones ( Fig. 5 ). Mandibles with three teeth in female and four in male ( Figs. 6, 7 ).

Fore and middle femora and tibiae of female widened. Hind tarsus 1.2–1.3 times longer than fore and middle tarsi in both sexes. Fore tibia longer than middle tibia 1.3 times in female and 1.2 times in male. Hind tibia longer than middle tibia, 1.5 times in female and 1.3 times in male. Fore femur of male without sensory field. Ratios of length to width of femur, tibia and tarsus given in Table 1 . Ratio of length of apical hind tarsomere to total length of hind tarsus 0.32 in male and 0.35 in female ( Fig. 8 ). Trochanter and femur of male with long, thin chaetae. Ventral surface of femora, tibiae and tarsi without spine-like macrochaetae in both sexes. All tibiae with 1–2 lateral, relatively long, colorless, thickened macrochaetae. Pretarsa with two well-developed claws and arolium with flexible pad between them ( Fig. 9 ).

Urocoxites I and V–VII with 1 + 1, II–IV with 2 + 2 eversible vesicles. Posterior angle of urosternites II–VI 74–80°, VII about 85° in both sexes. Length ratios of urosternites, urocoxites and urostyli given in Table 2 . Inner posterior lobes of female urocoxites VII protruding. Ratio of length to total width of protruding lobes about 0.34.

Thoracic tergites, urotergites I–IV, all urosternites, urocoxites I–V without macrochaetae in both sexes. Distribution of sublateral spines on urocoxites and urotergites given in Table 3 . Urocoxites IX with 2–3 + 2–3 outer spines in both sexes and with 6–8 + 6–8 inner sublateral spines in male and 7–11 + 7–11 ones in female ( Figs 10, 13 ).

Ovipositor slender, elongate, visibly surpassing apex of styli IX ( Fig. 10 ). Anterior and posterior gonapophyses with approximately 38–40 or 41–43 divisions, respectively. One or two basal divisions of anterior gonapophyses and 20–21 basal divisions of posterior gonapophyses glabrous. Distal spines of gonapophyses as long as 3–4 apical divisions combined. Apical divisions of anterior and posterior gonapophyses with 8–9 and 5–8 chaetae, respectively (not including apical spines) ( Figs 11, 12 ).

Male genitalia with one pair of parameres on urite IX. Parameres with 1 + 5 divisions ( Fig. 12 ), surpassing apex of penis. Penis and parameres clearly not attaining level of apex of urocoxites IX, ratio of the distance between apexes of penis and of urocoxites IX to width of distal division of penis 5.0–6.5. Basal division of penis 1.3–1.4 times longer than distal division ( Fig. 14 ).

Material examined. Holotype: male (on slide) ( ZIN); Abkhazia , Ochamchira District , Otap , Aymara, W Caucasus, 42°56′N, 41°31′E, elev. 440 m, Kotsha Cave, ˗20 to ˗ 25 m depth, on wet stoneflows, 20.09.2018 ( R. S. Vargovitsh) . Paratypes: 2 males, 7 females (one male and two females on slides); same locality and data ( R. S. Vargovitsh) ( ZIN) .

Habitats. All specimens of Coryphophthalmus troglophilus sp. nov. were collected on walls, stalagmites and among stones in a cave at depths of ˗20 to ˗ 25 m. The cave is narrow, almost all vertical, with a total depth of ˗ 33 m ( Fig.14 ). The arthropod fauna in the cave is quite rich. The main adaptations of this new species to life in conditions of low light on the rocky surface substrate include green or dark green eyes; weak body pigmentation; pretarsa with well-developed arolium and claws; relatively long cerci, tarsi and tibiae of the hind legs; apical needles of the urostyli; large sublateral spines on urocoxites IX, especially in the male; reduced number of apical sensorial cones on the third labial palpomere and sensilla on the apical part of labium; and camouflaged by the mottled color of scales on the upper side of the body. These characteristics place it as a troglophile.

Etymology. The species name troglophilus is Latin for “troglo = cave; philus = preference”.

Discussion. Coryphophthalmus troglophilus sp. nov. resembles C. abchasicus in the presence of numerous long thin chaetae on the undersurface of the male maxillary palp, absence of such chaetae on the upper surface of the male labial palp and absence of spine-like chaetae on the undersurface of the tarsus. The main differences between C. troglophilus and C. abchasicus consist in the color of compound eyes, the line of eye contact, lengths of cercus and apical spines of the urostyli, ratio of length to width of the apical palpomere of the labial palp and number of divisions of the ovipositor and parameres ( Table 4 ).

Figures

FIGURE 2. Coryphophthalmus troglophilus sp. nov. A—holotype, male, in situ; B—paratypes, females, in situ (photos R. S. Vargovitsh, 20.09.2018)

FIGURES 3–9. Coryphophthalmus troglophilus sp. nov. 3–5, 7–9, holotype male; 6, paratype female. 3) Eyes and paired ocelli, front view. 4) Maxillary palp. 5) Labial palp, with part of labium. 6, 7) Distal part of mandible. 8) Tarsus and tibia of hind leg. 9) Pretarsa of hind leg. Scale bars: 0.1 mm.

FIGURES 10–14. Coryphophthalmus troglophilus sp. nov. 10–12, paratype female; 13, 14, holotype, male. 10) Urocoxite IX and anterior gonapophyses. 11) Distal divisions of anterior gonapophyse. 12) Distal divisions of posterior gonapophyse. 13) Urocoxite IX and paramere. 14) Penis. Scale bars: 0.1 mm.